Fibronectin, a 440,000 dalton glycoprotein produced by fibroblasts, monocytes and endothelial cells; circulates in human plasma at concentrations of 300 Mug/ml; associates with fibrin upon activation of the clotting system; and is deposited at sites of inflammation and wound healing. The fibronectin deposition in these sites is both plasma-derived and cell-derived and is associated with proliferating, migrating and localizing cell populations including monocyte/macrophages, endothelial cells, epidermal cells and fibroblasts. In vitro plasma or cellular fibronectin can bind to a substratum of collagen or fibrinogen and simultaneously bind to fibroblasts. These data taken together suggest that fibronectin may provide a critical link between cells and their substrata especially during tissue remodeling. We propose to test this hypothesis by investigating how plasma and cellular fibronectin or fibronectin fragments effect normal human cell adherence and chemotaxis in vitro and cell localization in vivo. We have or will develop quantitative, reproducible assays for study of human monocyte, endothelial cell, epidermal cell and fibroblast adherence to protein substrata to determine whether normal human cells require fibronectin in their attachment to biological substrata as do cell-lines (Aim 1) and to study whether the requirement for fibronectin is the same among the various human cell types. To address the latter issue multiple parameters in the adherence assays will be varied to delineate time course for adherence, tenacity of adherence, optimal amounts of fibronectin for adherence and other optimal conditions for adherence of each cell type (Aim 2). Since we have already demonstrated that fibronectin enhances monocyte adherence we will investigate mechanisms by which this may occur by altering the protein (Aim 3) and modifying the cell (Aim 4). In addition, we will investigate whether fibronectin or fibronectin fragments recruit cells by means other than cell adherence. Specifically, we have shown that fibronectin fragment(s) stimulate monocyte chemotaxis and will determine whether these proteins stimulate chemotaxis of normal human fibroblasts, epithelial cells and endothelial cells (Aim 5). We will also delineate the mechanism(s) by which chemo-attractive fibronectin fragments for monocytes are generated and isolate the active fragments (Aim 6). Furthermore, we will investigate whether fibronectin or fibronectin fragments recruit cells in vivo (Aim 7). Our ultimate goal is to understand the role of fibronectin or its digestion products in human inflammatory dermatosis and wound healing.